The invention relates to a data carrier archiving system with a data carrier store comprising a plurality of storage compartments and at least one disk drive for data carriers and with a data carrier transport unit movable in the space in three different spatial directions by means of a handling unit for transporting the data carriers between different compartments of the data carrier store and/or the at least one disk drive.
In this respect, a data carrier is to be understood as any storage medium for symbols which is in a position to store pictures, language, music or other data.
Data carrier archiving systems of this type are known from the state of the art. In the case of such data carrier archiving systems, there is always the risk that stored and updated information concerning the position of the data carrier transport unit, which is provided for the control of the handling unit for moving the data carrier transport unit, either becomes lost or displays errors with increasing operation of the data carrier archiving system and so a point in time arrives, at which the data carrier transport unit is no longer in a position, on account of inexact positioning, to grip a data carrier, for example, in the compartment of the data carrier store provided for this correctly and reliably.
For this reason, it is necessary to provide the handling unit for the movements of the data carrier transport unit again with correct position information concerning the exact position of the data carrier transport unit; this can, for example, be carried out in that manual, so-called xe2x80x9cteach processesxe2x80x9d are carried out, with which the data carrier transport unit is moved manually to a predetermined position which then serves as reference position for the further movement of the data carrier transport unit by means of the handling unit.
The previous solutions for the exact determination of the position of the data carrier transport unit are all very time-consuming and sometimes very complicated and so the checking of the position of the data carrier transport unit is avoided when it is not absolutely necessary.
The object underlying the invention is therefore to improve a data carrier archiving system in such a manner that checking of the positioning of the data carrier transport unit is possible with measures which are as simple as possible.
This object is accomplished in accordance with the invention, in a data carrier archiving system of the type described at the outset, in that the data carrier transport unit is provided with a position detection unit, by means of which scanning of a reference object can be carried out after random operational phases for the exact determination of a position of the data carrier transport unit in at least one of three different spatial directions.
The advantage of the inventive solution is to be seen in the fact that by means of the position detection unit and a reference object provided for this an ascertainment of the position of the data carrier transport unit is possible in a simple manner and without considerable time being required.
This can be realized particularly favorably when the position detection unit optically detects a position of an object of measurement influenced by the position of the data carrier transport unit in the space relative to the reference object.
As a result of the optical detection of the positions of the object of measurement, the position detection can be realized, on the one hand, quickly and, on the other hand, also inexpensively since an optical detection of an object of measurement can be carried out with inexpensive constructional units.
A particularly simple solution which also ensures a high measurement accuracy provides for the position detection unit to be arranged on a housing of the data carrier transport unit so that its position can be detected as exactly as possible.
With respect to the design of the object of measurement itself, the most varied of solutions are conceivable. For example, one advantageous embodiment provides for the object of measurement to represent a part of the data carrier transport unit which can interact with the reference object. Such an object of measurement forming part of the data carrier transport unit could be, for example, a measurement arm provided on the data carrier transport unit, the individual positions of which are monitored when this is in mechanical interaction with the object of measurement.
With respect to the design of the reference object, no further details have been given in conjunction with the preceding description of the individual embodiments. One advantageous embodiment, for example, provides for the reference object to have, for example, the shape of a cube with known dimensions.
However, in order to be able to scan the reference object advantageously with the movable measurement arm, it is provided for the reference object to have the shape similar to that of an area of the data carrier which interacts with the at least one gripping arm during the gripping of this data carrier.
A particularly simple solution from a constructional point of view provides for the at least one measurement arm to be mounted on a support member thereof so as to be movable, preferably pivotable.
In a particularly favorable embodiment, it is provided for the support member, for its part, to be movable in a gripping direction relative to the data carrier transport unit.
In order to be able to use the measurement arm as object of measurement with as little resources as possible, it is preferably provided for the at least one measurement arm, held standing in a starting position by an elastic biasing means, to be movable out of its starting position contrary to the action of the elastic biasing means. Such a solution has the advantage that a position which is always taken up automatically by the measurement arm is already predetermined mechanically by the elastic biasing means and so, with respect to the monitoring of the individual positions, a starting position is available, into which the measurement arm returns automatically when it is not acted upon.
Thus, the position detection unit may be designed in a particularly advantageous manner when the position detection unit detects deviations of the at least one gripping arm from the starting position. In this respect, two positions of the measurement arm are sufficient in the simplest case. It is, however, even more advantageous when more than two positions may be detected.
In order to increase the sensitivity of the position detection even more, it is preferably provided for the position detection unit, with a predetermined movement of the at least one measurement arm, to detect regions of the measurement arm moving to different extents, wherein the advantage is to be seen in the fact that it is possible, with as precise a detection of the respective position of the measurement arm as possible, to detect regions moving to a greater extent during the predetermined movement of the measurement arm whereas, when the precision is intended to be less great, it is sufficient to detect regions of the measurement arm moving to a lesser extent.
The detection of regions of the measurement arm moving to different extents may be preferably realized in a simple manner during the detection of the pivot position since these regions move to different extents during the movement of the measurement arm depending on their radial distance.
In order to be able to have access to the data carrier in an advantageous manner, it is provided for the measurement arm to be movable in a gripping direction relative to the housing of the data carrier transport unit in order to interact with the reference object and for the position detection unit securely arranged on the housing of the data carrier transport unit to detect different measurement sections of the at least one measurement arm in different positions of the measurement arm in the gripping direction so that the movement of the measurement arm relative to the housing of the data carrier transport unit can be utilized to change, at the same time, the measurement sections of the measurement arm used by the position detection unit as objects of measurement.
A measurement arm represents an additional part and, when this is intended to be used, has to be brought first of all into the position of use relative to the other elements of the data carrier transport unit and so, for this purpose, further additional elements have to be provided on the data carrier transport unit.
For this reason, a particularly favorable solution with respect to its construction and thus also with respect to costs provides for the object of measurement to be at least one movable gripping arm of a gripper means of the data carrier transport unit, the positions of which can be influenced by contact with the reference object effectable in accordance with the positioning of the data carrier transport unit in the space.
The advantage of this solution is to be seen in the fact that the at least one gripping arm of the gripper means of the data carrier transport unit, which is movable in any case, is now used not only for gripping the data carriers but also, at the same time, can be used to represent an object of measurement for the position detection of the reference object.
Thus, reference can be made advantageously during checking of the correct position of the data carrier transport unit relative to the reference object to types of movement of the gripping arm serving as object of measurement which also occur during gripping of a data carrier and so it is no longer necessary to provide the gripping arm, for example, with additional movement possibilities which are required in order to use this successfully as object of measurement for the position detection unit.
The position detection of the object of measurement may be carried out particularly simply when positions of the at least one gripping arm, which are taken up by the gripping arm during gripping of one of the data carriers, can be detected with the position detection unit. With respect to the construction of the position detection unit, there is thus merely the task of detecting the individual positions of the gripping arm which it would carry out in any case during the gripping of a data carrier.
In order, furthermore, to detect the gripping position of the gripping arm in a defined and precise manner, on the one hand, and, on the other hand, to also be able to monitor the remaining positions of the gripping arm with adequate precision, it is preferably provided for the position detection unit to detect a gripping position of the at least one gripping arm corresponding to a gripped data carrier and deviations from the gripping position.
In this respect, it is particularly advantageous when the position detection unit detects deviations from the gripping position in the direction of a release position of the at least one gripping arm and alternatively or in addition thereto it is favorable when the position detection unit detects deviations of the gripping arm from the gripping position in the direction of the starting position so that the position detection unit is in a position to ascertain the direction, in which the position of the gripping arm deviates from the gripping position.
In this respect, it is particularly favorable when the position detection unit detects in the gripping position of the gripping arm the section of the gripping arm which has the greatest radial distance from the pivot axis. It is advantageously provided for the gripping position of the gripping arm to occur when the gripper means itself is also in gripping position, i.e. in its maximum position advanced in the direction towards the data carrier or the reference object.
This solution is particularly advantageous due to the fact that in the gripping position a very precise detection of the position of the gripping arms is required in order to be able to ascertain exactly whether, for example, the gripping jaws have engaged in the recesses provided for them in the desired manner.
Furthermore, one advantageous solution provides for the position detection unit to detect, during detection of the deviation from the starting position, the measurement section of the gripping arm which has the smallest radial distance from the pivot axis, wherein the advantage is to be seen in the fact that first of all a precise detection of the gripping arm as object of measurement is not required when it is leaving the starting position and so the detection of a measurement section of the gripping arm having the smallest distance from the pivot axis is sufficient.
With respect to the positions to be passed through by the gripping arm, it has proven to be particularly favorable when the gripping arm is movable during the interaction with the reference object from its starting position via an intermediate position corresponding to a gripping position into a release position and from this into the gripping position.
The inventive position detection unit may be used particularly favorably when the position detection unit detects two movable gripping arms of the gripper means interacting for gripping one of the data carriers as two separate objects of measurement.
The detection of two movable gripping arms as separate objects of measurement has the additional advantage that, as a result, an exact detection of the position of the data carrier transport unit is possible in an even simpler manner.
This may be realized particularly favorably when the position detection unit compares the positions of the gripping arms with one another in order to detect a position in a spatial direction extending in a direction transverse to the gripping direction and in a plane of movement of the gripping arms.
It is particularly favorable when the position detection unit detects a position in a spatial direction extending in gripping direction as a result of movement of the at least one gripping arm into the gripping position.
Furthermore, it is advantageously provided for the position detection unit to detect a position in a third spatial direction extending transversely to the first and second spatial directions as a result of movement of the gripper means in this spatial direction and additional movement in the second spatial direction and detection of the deviation of the gripping arm from the starting position. With this solution it is possible to use the gripping arm also for determining a position in a spatial direction which normally has no significance for the gripping arm. In particular, the gripper means can thus be used, for example, to detect an upper edge of an end side of a data carrier.
Alternatively to using at least one gripping arm as object of measurement for detecting the reference object, another advantageous embodiment provides for the object of measurement to correspond to the reference object.
For this purpose, it is favorably provided for the object of measurement to be a pattern detectable by the position detection unit, this pattern having markings reflecting optically differently and being associated with a spatially defined location, preferably a spatially defined location in the region of the data carrier store or the disk drives.
With respect to the detection of the pattern, the most varied of solutions are conceivable. For example, it is possible to take a complete picture of the pattern and analyze the individual markings in the picture taken, for example, by means of a digital camera.
Alternatively thereto, it is preferably provided for the position detection unit to scan the marking of the pattern with a reading beam. This solution is, in particular, very inexpensive since devices which generate a reading beam for scanning a pattern can be realized inexpensively.
A particularly simple possibility provides for the position detection unit to move the reading beam in a plane, wherein the reading beam is preferably a laser beam. In the simplest case, the laser beam of a bar code scanner and also the optical detection means may be used for this purpose.
In order to be able to scan it advantageously with the reading beam, the pattern can be designed in the most varied of ways. For example, one advantageous embodiment provides for the pattern to have a marking extending in a first spatial direction parallel to the reading direction.
In this respect, it is preferably provided for the first marking to have a defined extension in the first spatial direction detectable by the position detection unit, wherein the position detection unit preferably detects the extension in the first spatial direction via the time interval detectable on account of the change in the reflection in the area of the first marking.
In order to be able to carry out measurement in a second spatial direction, it is preferably provided for the pattern to have a second marking extending in a second spatial direction extending transversely to the first spatial direction. This second marking serves to detect the position in the second spatial direction. For example, it would be conceivable to detect the second marking by way of a reading direction extending in the second spatial direction.
However, when only one reading direction is available for reasons of as simple a solution as possible, it is preferably provided for the second marking to have an extension detectable in the first spatial direction and varying in the second spatial direction. It is thus possible to obtain information concerning the second spatial direction, despite a reading in the first spatial direction, in that the extension of the second marking in the first spatial direction varies in size depending on the position, in which reading takes place in the second spatial direction.
In order to have a reference parameter available for determining the extension of the second marking varying in the first spatial direction, it is preferably provided for a reference marking having a constant extension in the first spatial direction and independently of the second spatial direction to be associated with the second marking, this reference marking thus always supplying a reference value irrespective of the position, in which reading takes place in the second spatial direction, while the extension of the second marking varying in the first direction varies such that the varying extension can be placed in relation to the extension of the reference marking.
In order, in addition, to be able to determine a distance of the position detection unit from the object of measurement, i.e. from the pattern, it is preferably provided for the position detection unit to have a marking arranged in a defined reference position in relation to the moving reading beam.
In order to be able to determine a distance of the position detection unit from the object of measurement, i.e. from the pattern, it is preferably provided for the position detection unit to have a marking arranged in a defined reference position in relation to a starting point of the moving reading beam.
This marking associated with the position detection unit, which can likewise be read by the reading beam, creates the possibility of obtaining a reference value, in relation to which the extension of the first and second markings of the pattern can be placed.
This can be realized particularly favorably in that the marking is designed as a screen determining a defined extension in the first spatial direction, this screen creating the possibility of obtaining a fixed reference value for ascertaining the extension of the markings in the respective spatial directions.
In this respect it is particularly favorable when the position detection unit ascertains a distance between the position detection unit and the first marking from a ratio of the extension of the screen in the first spatial direction to the extension of the first marking in the first spatial direction.
Furthermore, it is preferably provided for the position detection unit to ascertain a position in the first spatial direction from a relative position of the extension in the first spatial direction defined by the screen in relation to the extension defined by the first marking.
Furthermore, it is particularly advantageous when the position detection unit ascertains a position in the second spatial direction on the basis of a ratio of the extension of the second marking in the first spatial direction to the extension of the reference marking in the first spatial direction.